NAD M51 – Digital Magic

As a competitive swimmer my first trip into audio was copying my hero Michael Phelps and getting a pair of Beats. With the help of Josh and a desire for more, I soon found that audio reproduction can be MUCH better. Look where we are now.

NAD are a staple name in the HiFi industry and they really do make something for everyone, be it the do it all D3020 we looked at, some headphones for when your out and about, or something a little shinier, a little more expensive and focuses on doing less stuff but better, welcome to the Master Series. I first encountered the Master Series at the press launch for BlueSound as there was a BlueOS module coming for the M12 and was impressed with just how stylish the products were but as they were not the focus of the day, I left bewildered on the Master series level of performance. Looking at the series, it seemed like the M51 direct digital DAC (with preamp) was the most fitting for my uses and fortunately could get hold of a unit. The M51 is not stupidly priced with it having a rather modest £1500 MSRP but you can now find it for around £1300.

What Does NAD Have Up Its Sleeve:

NAD haven’t skimped for features, they have turned this into a device not to dissimilar to the TARDIS, well in terms of DACs. I have got to a point where I personify DACs way too much, I have DAC problems. So lets run through the back of the M51, left to right, you ready?

Analog Line Outputs – XLR and RCA

Digital Inputs – AES, Coaxial, Optical, USB, 2x HDMI

HDMI Video Output

USB Port For Firmware Upgrades

RS 232 Port

IR In and +12V Trigger In

Mains Plug

No NAD, I don’t want my DAC to do anything more. The outputs are pretty standard, I have used the balanced output pretty much exclusively, as my amps like it and I tend to stick to USB for digital input. For the most part the digital inputs are pretty standard, but then there is HDMI and that’s were things are a little special because it opens up a few more options that most DACs don’t have access to. For example using this with Blu-Ray Audio and outputting the video back to the TV. Obviously by this I mean you can simply use it as a DAC in a TV set up, which is super cool.

I mentioned that this DAC also works as a digital pre-amp. This is done by obviously using either of the XLR and RCA outputs into a power amp and changing the volume setup to variable output instead of fixed. For the fixed output you can also manually select what the gain it is set at. This is all controlled from the included remote, which is actually also what comes with NAD’s M50. Being the M50 remote it has a lot of options on it, which has been a little confusing because the majority of buttons don’t actually do anything for the DAC. I would rather a much simpler remote dedicated to the M51, I don’t feel that is to much to ask. What it can do other than the volume set up is toggle auto off, the display brightness, volume control if using a pre and directly switch you to a different digital input. While the remote does have a lot of junk on it, the metal faceplate feels great and the remote is an ideal size, as to not get lost easily.

Now most interesting when you come across this DAC though is its boasts of doing 35/844. Huh? I don’t have any of that; I have 24/192, hell even some 32/384 files but not a single 35/844 song. Not to worry, you shouldn’t, in fact this DAC doesn’t handle anything more than 24 bit music with no higher a sampling rate than 192kHz. It doesn’t do DSD either. What it does do is convert all your files into 35 bit files and sample them at 844kHz, regardless of the original format.

You see it converts your music from PCM (pulse code modulation) to PWM (pulse width modulation), which funnily enough is the same native digital to analog conversion format as DSD. So on the fly it converts you music into PWM and then converts it into analog and I know what you’re thinking, that’s a lot of hassle. Well according NAD there is a lot of benefits such as eliminating jitter. To me well my ears have always told me I prefer DSD, which is also PWM, albeit working a completely different 1 bit configuration and if they are trying to capture how DSD sounds with PCM, then good luck to them. The biggest shame is that they don’t use there PWM technology to do native DSD, instead using Audirvana +, I convert PWM to PCM and back to PWM when listening to DSD and you end up losing all of its magic, there obviously is a limit to how much converting should be done.

Do You Even Lift?

This is easily the best-engineered DAC to fall into my system. It oozes class and safety. Right out the box it shows its weight, it is real heavy. So heavy in fact you should see my guns now after curling the M51 for the last few days, the results are clear, NAD should send this with a protein shake for post installment. The main thing that strikes me though is just how solid it feels. The front plate is a solid metal panel of 1.5cm that is so thick compared to the likes of my Yulong D200, which cowers at a weedy ½ cm. The other thing you notice is just in general that it must be fairly thick because giving the D200 or even the more expensive Antelope Audio Gold, a tap you get a light, hollow donk. Tapping the M51 you get a meaty thud. Don’t worry, I was gentle, no DACs were harmed during these tests. Buttons also have a nice click, of which there are two and the display is a bright and clear blue, which with the lights dimmed, looks great with the blue LEDs of my Questyle CMA800R I have spent a lot of time pairing this with.

One thing I have noticed as well is how it never really heats up. In fact it is quite the opposite, it is always quite chilly.

The only bit about the build that annoys me is the two big bolts that run down both sides. Yes I guess they have to be there so I can’t really complain but they really do stand out. That being said it is preferable to them being on top of the unit.

Let’s Take a Listen to PWM:

Well that’s a silly statement I know, you of course don’t listen to PWM and if I am honest, if there was a way in my head I imagined it sounding, this DAC isn’t that. You see I have a vast DSD collection and when it is decoded well, in native by a good DAC, I find it warm, smooth, enveloping and I’m going to say it, fairly analog. Yes that is the main reason I love DSD so much, it sounds so much more natural and analog. Well that is not something I am hearing with this DAC. Not in a bad way as while this really doesn’t sound analog like some DACs, it is probably the best digital sounding product I have tried. What am I getting at here? Well the Teac UD-501 for example is warm and smooth, for that reason I would say it is quite analog sounding, but in general, it is an average but analog sounding DAC. The Antelope Zodiac Gold on the other hand sounded analog but done so in a great way. Then my Yulong D200 sounds rather, in fact very, digital but the NAD does that digital sound a lot better.

Now digital sounding is of course only a way of describing sound, you can’t hear digital, you only ever hear analog but it is in line with the stigma that using digital files in comparison to a turntable is bitty and cold. That being said I don’t think me saying something is digital sounding is necessarily a bad thing, not even close. Digital tends to be very wide sounding, with great stereo separation and have immense detail and clarity. These are some of things that really strike me with the M51.

Detail is probably the main one, compare it to every other DAC in my collection right now (of which there are a few) and this gives you the best micro detail retrieval, it pulls up every breath in between notes, every mis-dampen of the fret board of a guitar and even a background cough in the studio. This does it. It really is one hell of a clinical DAC, it doesn’t smooth over anything, and it gives it to you, the good, the bad and the ugly. Well that’s what music has right.

Onto soundstage and it is wide, it pans on a horizontal plane quickly and effectively and likes to show off how spread out it can get. However it is not the most immersive, the Antelope Zodiac Gold had depth as well as width and it used all it dimensions to sound huge. While this does sound wide and airy it has never sounded huge to me or enveloped me in a pool of sound.

The sound is pretty darn neutral. Not pushing cold with a very smooth, extended and airy treble. In fact the upper frequencies are exactly what you want, it is bodied and detailed yet it doesn’t get out of hand. The Yulong was a little cold and the Aurender Flow could get just a little bit splashy. No this is spot on in tone, never showing too much decay or harshness. Even when using a headphone like the Sennheiser HD800. The midrange keeps that tone, detailed but controlled, never trying to do much. I do find the mids to just be a little well, shy. Not in the sense of being recessed, oh no they are exactly where they are meant to be. They just don’t engage me or do anything special. If anything I find them a little boring for no explainable reason. They give me detail, they are balanced but for some reason they still leave me craving.

The bass is also very behaved, maybe being a tad on the shorter side in terms of decay. That being said it extends as far down as any of the gear your using it with. Paired with the Aurorasound HEADA and Apollo Audio Lab X1 the deep bass was on course to giving me a headache. I like the bass, it lets the amplifier show its colours and your headphones or speaker even more so.

This DAC is one of them consistent performers. Never trying to wow you on first listen. It stays hidden, in the background as a DAC is and just keeps putting the work in, supplying your amp with details and speed. The first time Josh came round after me having this in my system (something he knows well) he didn’t seem to taken, “is the DAC all that” he asked me. I let him compare to his Teac UD-501 he had bought round, his Henry Audio 128 MK2, my Aurender Flow and even the Yulong D200. It was a great educational experience for the both of us as we were reviewing all them other DACs and this highlighted their shortcomings. We then went back to the NAD M51 and listened for a couple of hours and after we both appreciated so much more what the M51 does. It is consistent, not bringing too much, changing anything or even trying to wow, but it has impeccable balance and detail and that is darn impressive.

So What Do I Think?

The build quality sums up this DAC in many ways, solid. It is not the best DAC I have heard, let alone the best I have used in my system but not once have I felt that it has held back what comes after the M51 in my component chain. Personally I wish it had more depth and was just a little more musical but then if I want musical I can always plug my ZMF Vibros into my amp, they give me that. At its given price it does everything you would be expecting and for that reason I cant see why you shouldn’t consider it. Throw in the ability to use with HDMI sources, something you don’t often see and the pre-amp functionality (both which I have not used, I use a computer/headphone set up, no HDMI or power amps) that you don’t always get and these just add to the potential of the product. NAD have showed me that they have the ability to try something new (PWM) in DAC technology and deliver, count me impressed.